Motor driven automatic gun



My 4, 1965 J. G. ROCHA 3,181,423

MOTOR DRIVEN AUTOMATIC GUN Filed Feb. 1'7. 1961 5 Sheets--SheerI 2 26 ECp- IN V EN TOR.

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May 4, 1965 J. G. ROCHA 3,181,423

MOTOR DRIVEN AUTOMATIC GUN Filed Feb. 1'?. 1961 5 Sheets-Sheet 5INVENTOR.

Y have :not been entirely successful.

United States Patent C) M 3,181,423 M'IR DRIWEN AU'IGMATIC GUN John G.Rocha, Westfield, Mass., assigner to the United States of America asrepresented by the Secretary of the Army Filed Feb. 17, wel, Ser. No.90,147 7 Claims. (Cl. t39-l6l) (Granted under Title 35, US. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the Goverment for governmental purposes Without the payment ofany royalty thereon.

This invention relates to automatic machine guns of the type wherein thebarrel moves forwardly out of battery position upon the firing of eachround and is more particularly directed to means for operating a -gun ofthisitype through an external source of power. Y

In automatic machine guns of the type whereinV the actuating parts areenergized in direct response to the forces generated by the dischargeoff the `amn'iunition therefor, the rate of fire is generally fixed dueto the difliculties involved in varying the accelerations and speeds ot'the moving pants. However, present day military requirements demandconsiderable flexibility in the rate of fire in order to permit equallysatisfactory operation for ground use or in vehicles, such 'as aircraftor tanks, both Vduring attack or defense against a variety of targets.

Previous attempts to provide a variable rate of fire, which would permitthe operator of the gun to select the particular rate bestsuited to thetactical use then required, For example, the use of hydraulic buffermechanisms for decreasing the rate of re requires `additional space forthe storage of special uids while the use of mechanical or springdevices for temporarily interrupting the travel of the recoiling partsintroduces relatively ,complex Iassemblies easily susceptible tomalfunction. l

lthas, therefore, been proposed that the gun be continuously driven byan external source `of power, such as an electric motor having avariable output. However, the use of -this source Vof energy hasheretofore been limited to Weapons with revolving chambers or a rotatingcluster of barrels.

Accordingly, it is a broad object of this invention to ,Y utilize anexternal source of electrical energy for operatbarrel is adapted to bemoved rearwardly into battery positiomand-the pivotal hammer employed toenergize a longitudinal striker is arranged to be cocked by the rearwardmovement of the barrelinto lockedbattery position thereby preventingthepossibility of firing in the event the barrel fails to functionproperly.

Still another object of this invention lis the provision ,of anautomatic gun of the aforesaid type wherein the locking `of the ybarrelin battery position ,and vthe release of the cocked hammer effected insequence by the same cam track in a rotatable operating drum therebyassuring the completion of locking prior to the vinitiation of firing.

An additional object of this invention lies inthe provision of an.automatic gun of the aforesaid Vtype wherein the cycling of thereciprocal barrel is not dependent upon the ring of `a round therein sothat a failure to feed will not interrupt the continuity of automaticfire.

A specificV object of this inventionis the provision of an extremelycompact and reliable gunof the aforesaid 3,181,423 retainedv May 4, reesICC FIG. 2 is an enlarged elevationalcross-section of the rear portionof the gun showing the barrel in battery position immediately prior tolocking thereof and also show ing the hammer in the cocked position;

FIG. 3 is a view similar to that of FIG. 2 but showing the parts in 4theposition assumed at the instant of ring;

FIG. 4 is an enlarged cross-section taken along lines 4 4 in FIG. 1 toshow the conguration of the locking cam inthe operating drum;

FIG. 5 is a cross-sectional View taken along line 5 5 in FIG. 1 throughthe hammer cooking plunger and the hammer Sear;

FIG. 6.is la cross-sectional view taken along line 6-6 Y in FIG.v 1 toshow the structural details of the hammer and scar mechanisms as seenfrom the rear;v

FIG. 7 is a cross-sectional View taken along line 7-7 in FIG. 2 to showthe details of the sear release mechanism in the cocked position of thehammer;

FIG. 8 is a cross-sectional view taken along line @-8 in FIG. 2 to showfurther details of the sear'release mechanism;

FIG. 9 is a cross-sectional view taken along line 9--9 in FIG. 3 in amanner similar to that of FIG. 7 but with the hammer and sear mechanismsshown in the tiring positions thereof;

FIG. 10 is a cross-sectional view taken along line tti-ttl in FIG. 3 ina manner similar to that of FIG. 8 but with the hammer and searmechanisms shown in the lining positions thereof; and

FIG. ll is an enlarged exploded perspective view of the entire firingmechanism.

As illustrated in the drawings, the gun of the present inventionincludes a substantially rectangular receiver l2 having ra bifurcatedextension 14 projecting from the rear end thereof for straddling ahousing l5 which is releasably secured thereto -for containing a firingmechanism as will be hereinafter described. Receiver 12 is also providedwith a forwardly opening bore i6 for slidabiy receiving a barrel 1S.Rotation of barrel t8 in reiver 12 Y `-gun to any suitably fixed bracketkor hanger 26 in which the required mating slots 23 are formed. Receiver12 is open along the underside thereof, :as `best shown at Sti, andV isprovided with depending front and rear drum supports 32 and 3drespectively secured thereto on either vside, of opening 3h.

`Supports 32 and 34 are joined by'a rotatable shaft-36 on which iscentrally mounted a hollow cylindrical oper- `atingdrum 38. An electricmotor 4d having a variable ,output is secured to rear drum support 32 sothat the projecting spindle 42 on motor eti engages in the rear end ofshaft 36 to impart clockwise rotation to drum 33, If necessary, motor4t) may be replaced by a suitable cranking device whichwill permitmanual rotation of drum 33. The exterior periphery of drum 3S is formedwith a continuous cam track 44 of suicient width to receive the enlargedhead of a follower 46 protruding from the underside of key portion onbarrel 18. Cam track 44 is generally helical in configuration, butincludes a straight dwell portion for a purpose to be hereinafterexplained. Thus, the rotation of motor 40 imparts longitudinalreciprocation to barrel 18 away from and toward battery position inreceiver 12.

A pair of bearing rings or collars 48 are preferably integral with theexterior of barrel 18 and are sufliciently spaced apart to ensure thatin any position of barrel 18 the exterior periphery of at least onecollar will remain in contact with the interior surface of receiver bore16. This construction allows barrel 18 to distort slightly during thelongitudinal travel thereof without binding in receiver bore 16.However, at the instant of ring a round in barrel 18, both collars 48are in contact with the interior periphery of bore 16 toinsure maximumaccuracy in the Hight of the projectile.

A barrel lock 50 is slidably disposed in the upper end of d rear drumsupport 34 and is arranged to pass through a suitable slot 52 in theunderside of receiver 12 and engage in a locking recess 54 formed in theunderside of barrel 18. Barrel lock S0 is actuated into and out oflocking position through the camming engagement between a cam follower56 thereon and a cam track 60 formed into the rear face of drum 38. Camfollower 56 is xedly secured in barrel lock 50 and projects forwardlytherefrom through a vertically elongated opening 58 in rear drum support34. As best shown in FIG. 4, cam track 60 is circular in configurationexcept for an angular locking portion 62 and an oppositely inclinedunlocking portion 64. Cam portions 62 and 64 are sufficiently spacedapart to form a dwell portion 66 for a purpose to be shown. The width ofdwell portion 66 is slightly less than the corresponding width of dwellportion 45 in barrel cam track 44 in order to ensure continuous positivecontrol of barrel lock 50 in the locking position thereof despite anyadverse accumulation of tolerances.

Immediately above cam follower 56, barrel lock 50 is provided with avertically disposed inverted T-slot 74 having inclined grooves 76 formedinto the opposite sidewalls thereof. The rear end of follower 56 isnotched, as indicated at 78, at the angle which will prevent anyblocking of grooves 76. A Sear release plunger 80 is longitudinallydisposed for slidable reciprocal movement in the upper portion of reardrum support 34 and is provided with a substantially rectangular forwardend 82 having a portion thereof sufficiently reduced in thickness alongan inclined path coextensive with grooves 76 in barrel lock 50 to formopposing shoulders 84 for mating engagement therewith. The rear end ofplunger 80 is arranged to project from the rear of drum support 34 intothe hollow interior of housing 15 and is provided with a rectangularportion 86 terminating in an enlarged head 88 having a beveled sideface, as best illustrated at 90 in FIG. ll, for a purpose to behereinafter explained. Rectangular portion 86 of sear release plunger 80containsa longitudinally elongated slot 92 for the passage therethroughof a transverse pin 94 on which a sear carrier 96 and a hammer 98 arepivotally mounted.

Sear carrier 96 is provided with a pair of spaced apart mounting lugs100 on the underside thereof which straddle the rear end of sear releaseplunger 80 and are suitably bored, as indicated at 102, to align withelongated slot 92 for the passage of mounting pin 94 therethrough. Atorsion spring 104 is arranged to surround the outer end of transversepin 94 and lie between the outer mounting lug 100 and the rear end ofsear release plunger 80. One end of spring 104 bears against theunderside of sear carrier 96 while the other end bears against the floorsurface in housing 15 thereby normally urging sear carrier 96 in aclockwise direction. The body of sear carrier 96 is centrally drilledinto one end thereof, as indicated at 105 in FIG. 5, to provide a seatfor a cylindrical sear 106 having a hollow interior arranged to house aspring 108. In addition, Sear carrier 96 is notched, as best shown at110 in FIG. ll, to provide a passage therethrough for the longitudinaltravel of plunger head 88 and is slotted, as illustrated at 112, alongan axis parallel to the centrally drilled hole 105 therein and incommunication therewith.

Rotation of sear 106 in carrier 96 is prevented by a relatively narrowbar 114 integral with otherwise secured to the underside of the sear, asbest shown in FIG. 1l, and engageable in sear carrier slot 112. Whenscar 106 is properly assembled in carrier 96, spring 108 urges theopposite end of sear 106 into engagement with a horizontally elongatedopening 116 formed into the side of hammer 9S. One end of sear bar 114extends slightly beyond the corresponding end of sear 106 while theopposite end of bar 114 stops short of the other end of sear 106 toterminate in a laterally inclined cam surface 118. When Sear 106 is inengagement with hammer 98, cam surface 118 on bar 114 lies in the pathof the beveled side face 90 of head 88 on Sear release plunger 80.

Hammer 98 is pivotally mounted at the lower end thereof on transversepin 94 and is provided with a solid head 120 adapted to strike theprojecting rear end of a firing pin 122 slidably mounted in the rear endwall of receiver 12. This ring movement of hammer 98 is obtained throughthe medium of a spring-biased plunger 124 slidably seated within aninclined well 123 formed into the back wall of receiver extension 14 andbearing against an arcuately formed surface 128 on the rear of hammer98. The forward end of hammer plunger 124 is provided with an extension125 terminating in a surface 126 substantially parallel to the rear faceof receiver 12. The upper and lower surfaces of plunger extension 125are grooved, as shown at 127, for engagement by mating rails 129 formedalong the opposite walls of a T-slot 130 provided in the side wall ofhousing 15. Contact of hammer plunger extension 125 with the rear end ofreceiver 12 immediately prior to the impact of hammer head 120 withfiring pin 122 halts travel of hammer plunger 124 for a purpose to beshown.

Firing pin 122 is slidably mounted in a plug 131 threaded into asuitable counterbored opening 132 in the back wall of receiver 12. Plug131 is itself provided with a counterbore 134 to receive an annularflange 136 on firing pin 122 which serves as a backstop for the rear endof a spring 138 disposed within the smaller diameter portion ofcounterbore 134. Thus, firing pin 122 is normally urged rearwardly awayfrom the base of a cartridge 140 chambered in the rear end of receiverbore 16 and held therein by arcuate ribs 142 projecting in front of theconventional cartridge case rim 144.

A hammer cooking plunger 146 is slidably disposed in a longitudinal hole148 extending through the back wall of receiver 12. The forward end ofplunger 146 projects suiciently into receiver bore 16 to be contacted bythe rear end of key portion 20 during rearward movement of barrel 18into battery position. The rear end of plunger 146 is arranged tocontact a slabbed surface 150 formed on the front of sear carrier 96.Thus, plunger 146 serves to convert the rearward thrust of barrel 18into pivotal movement of sear carrier 96 which in turn moves sear 106 tocock hammer 98. The entire firing mechanism herein described in inclosedin a cover 152 fastened about housing 15.

When electric motor 40 is turned on to initiate rotation of drum 38, theengagement of cam follower 46 in helical cam track 44 will cause barrel18 to move in the same direction and from the same location as thatreached at the time motor 40 stopped during the previous cycling of thegun. If the parts are in the position of FIG. l, barrel 18 will begin tomove rearwardly over the chambered cartridge 140 which was previouslyfed into engagement with receiver ribs 142 by suitable feed mechanism(not shown). As barrel 1S approaches the battery position shown in FIG.2, key portion 20 thereon will force hammer cooking plunger 146 torotate s ear carrier 96 in a counterclockwise direction about pin 94.movement of sear `carrier 96 is imparted to hammer 98 through theengagement ofthe latter by sear 106 under the urgingof spring 108. Asshown in FIG. 2, hammer 98 is fully cocked when barrel 18 reachesbattery position and cam follower. 46 thereon enters the dwell orstraight portion 45 in cam track 44 on the exteriorof drum '38.

Cam track 60 is so located, in the rear face of drum 38 that camfollower 56 on barrel lock Si) will be contacted by the locking camportion 62 to lift barrel lock 50 into Vlocking recess 54 at the momentthe rearward movement of barrel 18 has terminated. As barrel lock S0 islifted, inclined grooves 76 therein cam sear release plunger Si)rearwardly. During this movement, the beveled side face of plunger 80rides along the inclined end of sear bar 114 and cams the projectingendof sear 106 into sear carrier 96 and out of engagement 'with hammer 98.The Vsubse-l quent firing movement of the hammer 98 is obtained throughthe bias of hammer plunger 124 which was -initially compressed duringthe cocking of hammer 98. The rearward movement of sear release plunger80 is terminated upon contact of the forward end of elongated slot 92Atherein with transverse pin 94. Y

The forward movement imparted to firing pin 122 by hammer 98 res thechambered cartridge 140. Dwell portion 45 of cam track 44 is arranged toprovide a barrel locking interval of sufficient length to ensure thedissipation of the residual gas Vpressure in receiver bore 16.Thereupon, cam follower 56 is contacted by the unlocking cam portion 64of cam track 60 to withdraw barrel lock 50 from engagement with barrel18. At this moment, the cam portion of cam track 44 begins to movebarrel 18 forwardly to permit feeding of the next cartridge 14) intochambering position in receiver 12.

Since the forward travel of hammer plunger 124 is halted by rear end ofreceiver 1,2 immediately prior to the completion of travel Vby hammer98, the absence of any load thereon in the position shown in FIG. 3permits liring pin spring 138 to force tiring pin 122 rearwardly againstthe weight of hammer head 120 to the extent required to retract the tipthereof out of the path of the incoming cartridge 140.

The aforesaid cycle of operation is repeated as long as motor 40operates to rotate drum 38 andsince the barrel is mechanically actuated,any failure to feed or ignite a cartridge will merely interrupt ratherthan halt continuous automatic tire. Moreover,'since locking of thebarrel in battery position must precede the vcocking of the hammer,accidental or premature tiring of a cartridge is positively prohibited.

In addition, the manner in which the motor-driven operating drum iscombined with a longitudinally reciprocal barrel adapted to moveforwardly out of battery position upon the firing of a cartridge reducesthe space required rearwardly of the breech and thereby creates anextremely compact gun which can be operated'in any desired position inwhich fixed mounting of the receiver can be effected.

. The greatest benet produced byrthe aforesaid novel combination ofparts lies in the ease with which the rate of fire can be varied fromone extreme to the other and thereafter maintainedin any rate selectedby the operator.

Although a particular embodiment of the invention has been described indetail herein, itis evident thatfmany variations may befdevised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.V

I claim: Y

1. In an automatic gun having a receiver with a longitudinal bore formedinto one end thereof for holding a cartridge in firing position, and abarrel slidablydisposed in the bore for reciprocable movement to andfrom battery position, the improvement of an operating drum rotat- Thispivotal '6 ably secured l to the receiver, a cam "follower projectingfrom the barrel, cam track means in said drum engageable Ywith saidfollower for continuously cyclingV the barrel forwardly from batteryposition and rearwardly in return thereto, and means responsive to therotation of said drum for firing the cartridge subsequent to movement ofthe barrel into battery position.

2. In an automatic gun having a receiver with a longitudinal forwardlyopening bore adapted to successively retain cartridges therein in afiring position, a barrel slidably disposedin the bore for reciprocalmovement into and out of battery position, an operating drum rotatablysecured to the receiver, a cam follower projecting from said barrel,camV track means in the exterior periphery of said drum engageable withsaid follower for cycling Ysaid barrel'forwardly away from batteryposition and rearwardly for return thereto, a barrel lock slidablydisposed in the receiver for reciprocal movement into and out of lockingengagement with said barrel, cartridge firing means operable in responseto the locking movement of said barrel lock, cam track means in the rearface of said drum for cycling said barrel lock in relation to thereciprocal movement of said barrel such that the latter is lockedagainst forward movement out of battery position during the interval inwhich the cartridge is fired and the resulting discharge gases arereduced to safe limits.

3. The combination defined in claim 2 wherein the receiver is open alonga portion of the underside of the bore therein and said barrel issurrounded by a pair of fixed bearing collars spaced apart to such anextent that at least one of said collars is in bearing contact with theinterior bore surface in the receiver at any instant during thereciprocal travel of said barrel, both of said collars being in saidbearing contact during the battery position of said barrel.

4, In an automatic gun having a receiver with a longitudinal forwardlyopening bore adapted to successively retain cartridges therein in atiring position, a barrel slidably disposed in the bore for reciprocalmovement into and out of battery position, the receiver having anopening thereto provide access to the barrel, an operating drumrotatably secured to the receiver with the exterior periphery thereofadjacent said access opening therein, electric motor means secured tothe receiver for rotating said drum, a first cam track formed into theexterior periphery of said drum and having a helical cam portion on bothsides of a dwell portion, a cam follower projecting from said barrelthrough said access opening in the receiver and into engagement withsaid first cam track for cycling said barrel forwardly away from batteryposition and rearwardly for return thereto, a barrel lock slidablydisposed in the receiver for reciprocal movement into and o ut oflocking engagement with said barrel, a second cam trackV formed into theend face of said drum and having a dwell portion included between apairof camming portions, a cam follower projecting from said barrel lockinto engagement with said second cam track, said first and second camtracks having said camming and dwell portions thereof respectivelylocated in said drum to provide alternate cycling of said barrel andsaid barrel lock whereby the former is locked against forward movementout of battery position until the cartridge has been red andthe residualgas pressure reduced to safe limits, and cartridge firing means operableby the locking movement of said barrel lock.

Y 5. The combination defined in claim 4 wherein said Vdwell portion insaid barrel cam track is of slightly greater width than the remainingcam portion thereof to pernormally urging said hammer into strikingcontact with said firing pin, a sear engageable with said hammer, meansresponsive to the rearward movement of said barrel into battery positionfor forcing said sear to cock said hammer, and a plunger camminglyengageable with said barrel lock whereby the locking movement of thelatter functions said plunger to withdraw said sear and release saidhammer against vsaid firing pin.

7. The combination defined in claim 4 whereby said cartridge tiringmeans comprises a spring-biased ring pin slidably Seated in the rear endof the receiver and normally urged away from contact with the cartridgein the iring position thereof in the receiver, a spring-biased hammerpivotally mounted in the receiver for striking contact with said firingpin, a sear carrier pivotally mounted in the receiver jointly with saidhammer, a springbiased sear normally urged into engagement with saidhammer, a hammer cocking plunger slidably disposed in the receiver forcontact with said sear carrier during the movement of said barrel intobattery position whereby the resulting pivotal movement of said carrieris imparted through said sear to said hammer for the cocking thereof,and a sear release plunger slidably disposed in the receiver for cammingsaid sear out of engagement with said hammer, said sear release plungerand said barrel lock having cooperating cam means for convertingreciprocal Vertical movement of said lock into reciprocal longitudinalmovement of said sear release UNITED STATES PATENTS 4/49 Corte 89-1595/58 Lyon 89-161 X BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL BOYD, Examiner.

1. IN AN AUTOMATIC GUN HAVING A RECEIVER WITH A LONGITUDINAL BORE FORMEDINTO ONE END THEREOF FOR HOLDING A CARTRIDGE IN FIRING POSITION, AND ABARREL SLIDABLY DISPOSED IN THE BORE FOR RECIPROCABLE MOVEMENT TO ANDFROM BATTERY POSITION, THE IMPROVEMENT OF AN OPERATING DRUM ROTATABLYSECURED TO THE RECEIVER, A CAM FOLLOWER PROJECTING FROM THE BARREL, CAMTRACK MEANS IN SAID DRUM ENGAGEABLE WITH SAID FOLLOWER FOR CONTINUOUSLYCYCLING THE BARREL FORWARDLY FROM BATTERY POSITION AND REARWARDLY INRETURN THERETO, AND MEANS RESPONSIVE TO THE ROTATION OF SAID DRUM FORFIRING THE CARTRIDGE SUBSEQUENT TO MOVEMENT OF THE BARREL INTO BATTERYPOSITION.